The R38 class (also known as the A class) of rigid airships was designed for Britain's Royal Navy during the final months of World War I, intended for long-range patrol duties over the North Sea. It was the largest one built with 14 gas cells and six Sunbeam engines. It was 700ft long and had a speed of 71mph. Four such airships were originally ordered by the Admiralty, but orders for three of them (R39, R40 and R41) were cancelled after the armistice with Germany, and work on the lead ship of the class, R38, continued only after the United States Navy had agreed to purchase her. At the time of her first flight in 1921, she was the world's largest airship. After the airship was completed at Cardington, Bedfordshire, it flew to RNAS Howden [Royal Navy Air Station] for test flights and where the full conversion to American livery was to be made.After some modifications to the rudder and elevators, a second test flight flew on 17 July to Howden for airworthiness and acceptance trials. Some testing of the re-balanced control surfaces was performed on this flight which resulted in severe pitching. When in the shed at Howden, examination of the structure revealed damage to several of the girders. These were replaced and others were strengthened but there were increasing doubts being expressed about the design including some by Air Commodore E. M. Maitland, the very experienced commander of the Howden base, who was to be one of those killed. The American designation ZR-2 was already painted on the hull before its four completed test flights and in preparation for a final trial flight and delivery to Lakehurst, New Jersey. Following a spell of bad weather the airship was finally walked out on 23 August and in the early morning took off for her fourth flight which had an intended destination of RNAS Pulham, Norfolk where she could be moored to a mast, a facility lacking at Howden. In the event mooring proved impossible because of low cloud and so the airship returned out to sea with the intention of running some high speed tests and then returning to Howden. The speed runs proved successful and as there was still daylight left it was decided to try some low altitude rudder tests to simulate the effects of the rough weather that could be expected on the Atlantic crossing. It was flying at an altitude of 2,500ft and at a speed of 60mph. At 17:37, fifteen degrees of rudder was applied over the city of Hull. Eye witnesses reported seeing creases down the envelope and then both ends drooped. This was followed by a fire in the bow and then a large explosion which broke windows over a large area. The airship had failed structurally and fell into the shallow waters of the Humber estuary. Sixteen of the 17 Americans and 28 of the 32 Britons in the crew were killed. The only American to survive was Rigger Norman C. Walker. The five who survived were in the tail section. This disaster resulted in more deaths than the more famous Hindenburg Disaster that killed 35. In 1924 a memorial was erected at the south-western side of Hull Western Cemetery where a number of the casualties were interred. It is made of Portland stone with bronze plaques. The free-standing stone chest is topped with a stone cross. The chest has two projections on either side to the front on which two bronze plaques are fixed.

The disaster memorial in Western Cemetery,Hull Yorkshire contains two plaques,one for the British and one for the American airmen who lost their lives. 44 out of the 49 on board perished.Some of the casualties are: